Nineteen genes in the set have a unique human ortholog (Table 2) and, of these, 12 (UBX4, IDP1, IDP2, MSH2, RAD1, TOP2, NBP2, MUS81, RAD54, DBF2, STP22, PBS2) are orthologous to cancer genes as annotated in the Cancer Gene Index (CGI [17]). This evidence concerns the gene MUS81 and cancer.